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Study: Swelling volcanoes could help predict eruptions in Alaska, elsewhere

Ben Anderson
The Drift river valley, coming off of the north side of Mt. Redoubt, is one possible path for volcanic debris from an eruption. November 1, 2012
Loren Holmes photo
Mt. Redoubt, one of four active volcanoes in the Cook Inlet region. November 1, 2012
Loren Holmes photo
Redoubt Volcano's summit, on the right, with steam from a fumarole on the left. November 1, 2012
Loren Holmes photo
A recently active fumarole on the north slope of Mt. Redoubt. November 1, 2012
Loren Holmes photo
Chisik Island and Tuxedni Bay, south of Mt. Redoubt. November 1, 2012
Loren Holmes photo
Jagged peaks of the Alaska Range near Mt. Redoubt. November 1, 2012
Loren Holmes photo
The east face of Mt. Redoubt, with mud flows clearly visible. November 1, 2012
Loren Holmes photo
The Drift River Oil Terminal, in the shadow of Mt. Redoubt, lies in one of the probable debris paths from the volcano. November 1, 2012
Loren Holmes photo
The Drift River Oil Terminal, in the shadow of Mt. Redoubt, lies in one of the probable debris paths from the volcano. November 1, 2012
Loren Holmes photo
Redoubt Volcano's summit, on the right, with steam from a fumarole behind the ridge on the left. November 1, 2012
Loren Holmes photo

A new study of Indonesian volcanoes conducted by two University of Miami researchers could hold vital clues to the future of predicting explosive eruptions from volcanic peaks around the globe.

Using data obtained from a satellite-based system known as Interferometric Sythetic Aperture Radar (InSAR), PHd student Estelle Chaussard and her advisor Falk Amelung were able to discern tiny movements in the earth’s surface near 79 volcanoes in the highly-volcanic west Sunda arc in Indonesia. They observed “inflation,” or a swelling of the earth at six volcanoes using data obtained between 2006 and 2009. In three of those six instances, the volcanoes erupted after observing the inflation.

The Sunda arc is home to 13 percent of the world’s active volcanoes, the authors note, and the observed swelling volcanoes had magma reservoirs at relatively shallow depths below the earth’s surface.

“Until this study we believed that the depth of a volcano's magma reservoir was highly individual but we show that in Indonesia we see a trend in the depths of magma reservoir,” Chaussard wrote in an email to Alaska Dispatch. “This might have been missed by previous studies because they were considering only one or two volcanoes but not an entire arc.”

The Sunda arc is located along a fault where the India and Australian tectonic plates are subducting -- or being pushed under -- the Sunda and Burma plates. Such subduction along volcanic arcs is relatively normal around the world, and Alaska’s Aleutian arc, located in the namesake islands in the northern Pacific Ocean, has a similar subduction occurring where the Pacific and North American plates meet.

All that is to say that the results seen in Indonesia -- where half of the volcanoes observed inflating later erupted -- might mean that the InSAR technology could have implications for remote observations of volcanoes in other places on the globe, including Alaska.

“I believe that similar results would be expected in the Alaskan arc,” Chaussard wrote. “Especially it is likely that several volcanoes of the Alaskan-Aleutian arc have shallow magma reservoirs because (of) a tectonic setting similar to Indonesia.”

Many Alaska volcanoes are already observed solely by remote or satellite monitoring systems, oftentimes relying on faraway seismic sensors or sporadic satellite imagery to provide updates on volcanoes conditions.

That’s the case with one volcano under watch right now by the Alaska Volcano Observatory, Cleveland Volcano, which has erupted numerous times in recent years, and remains at an elevated watch status. There is no real-time monitoring at the volcano.

Chaussard said that the InSAR technology could prove another valuable tool in the toolbelt of remote volcanic monitoring systems, especially as a predictor to potential eruptions.

“The InSAR technology allows us to survey larger areas than ground based networks and also costs less,” Chaussard notes.

“If magma accumulation beneath volcanoes can be detected remotely months before an eruption, steps can be taken to put the volcano under the ‘microscope’ with field studies (GPS, seismic, strain meters) to track the magma migration through the volcanic system and accurately forecast eruptions,” she wrote.

The study, “Precursory inflation of shallow magma reservoirs at west Sunda volcanoes detected by InSAR,” appears in the journal Geophysical Research Letters.

Contact Ben Anderson at ben(at)alaskadispatch.com